Estimation of acceptable daily intake values based on modeling and in vivo mutagenicity of NDSRIs of fluoxetine, duloxetine and atomoxetine.

Nitrosamine drug substance related impurities or NDSRIs can be formed if an active pharmaceutical ingredient (API) has an intrinsic secondary amine that can undergo nitrosation. This is a concern as 1) nitrosamines are potentially highly potent carcinogens, 2) secondary amines in API are common, and 3) NDSRIs that might form from such secondary amines will be of unknown carcinogenic potency. Approaches for evaluating NDSRIs include read across, quantum mechanical modeling of reactivity, in vitro mutation data, and transgenic in vivo mutation data. These approaches were used here to assess NDSRIs that could potentially form from the drugs fluoxetine, duloxetine and atomoxetine. Based on a read across informed by modeling of physicochemical properties and mechanistic activation from quantum mechanical modeling, NDSRIs of fluoxetine, duloxetine, and atomoxetine were 10-100-fold less potent compared with highly potent nitrosamines such as NDMA or NDEA. While the NDSRIs were all confirmed to be mutagenic in vitro (Ames assay) and in vivo (TGR) studies, the latter data indicated that the potency of the mutation response was ≥4400 ng/day for all compounds-an order of magnitude higher than published regulatory limits for these NDSRIs. The approaches described herein can be used qualitatively to better categorize NDSRIs with respect to potency and inform whether they are in the ICH M7 (R2) designated Cohort of Concern.

Genotoxic and oxidative effect of duloxetine on mouse brain and liver tissues.

We evaluated the duloxetine DNA damaging capacity utilizing the comet assay applied to mouse brain and liver cells, as well as its DNA, lipid, protein, and nitric oxide oxidative potential in the same cells. A kinetic time/dose strategy showed the effect of 2, 20, and 200 mg/kg of the drug administered intraperitoneally once in comparison with a control and a methyl methanesulfonate group. Each parameter was evaluated at 3, 9, 15, and 21 h postadministration in five mice per group, except for the DNA oxidation that was examined only at 9 h postadministration. Results showed a significant DNA damage mainly at 9 h postexposure in both organs. In the brain, with 20 and 200 mg/kg we found 50 and 80% increase over the control group (p ≤ 0.05), in the liver, the increase of 2, 20, and 200 mg/kg of duloxetine was 50, 80, and 135% in comparison with the control level (p ≤ 0.05). DNA, lipid, protein and nitric oxide oxidation increase was also observed in both organs. Our data established the DNA damaging capacity of duloxetine even with a dose from the therapeutic range (2 mg/kg), and suggest that this effect can be related with its oxidative potential.

Duloxetine-Induced Neural Cell Death and Promoted Neurite Outgrowth in N2a Cells.

Duloxetine is a clinical drug that is primarily used for treatment of depression and pain, but it has side effects of addiction and tolerance. Cytochrome P450 (CYP) is its metabolic enzyme, and the drug's biofunction results from its neuro-protective effect in animal and cell models. We aimed to investigate the duloxetine-induced neural cytotoxicity effect and its performance in an N2a cell neurite outgrowth model. Cell death was assessed as cell viability using a Cell Count Kit-8 and further evaluated using bright-field images, propidium iodide (PI) and annexin V staining, colony-formation analysis, TUNEL staining of the cells, and biochemical testing. N2a cells were committed to differentiation by serum withdrawal and RA induction, and the neurite outgrowth was evaluated as the number of differentiated cells, longest neurite length, and average neurite length. Cell cycle analysis, PI and annexin V staining, mRNA expression, and biochemical testing were used to evaluate the drug effects on differentiation. The induction of neural cell death by duloxetine was not affected by classic cell death inhibitors but was promoted by the CYP inducer rifampicin. N2a cell neurite outgrowth was promoted by duloxetine via reduction of the CYP2D6 and MDA levels and induction of Bdnf protein levels. Duloxetine induces neural cell death through effects on CYP and promotes N2a cell neurite outgrowth by regulating CYP, Bdnf protein, and the intracellular lipid peroxidation level.

Analysis of neurotransmitters in Daphnia magna affected by neuroactive pharmaceuticals using liquid chromatography-high resolution mass spectrometry.

Neurotransmission plays an essential role during the central nervous system (CNS) development. During the last years, several studies based on the changes produced in neurotransmitters of aquatic organisms caused by pharmaceuticals have been reported. Daphnia magna, the aquatic ecotoxicological model organism, shares several of the neurotransmitters targeted by antidepressant and other neuro-active drugs with vertebrates. Therefore, a method based on liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) has been applied for the first time to study the levels of 41 neurotransmitters in Daphnia magna under the effect of four different neuro-active pharmaceuticals (sertraline, venlafaxine, duloxetine and fluoxetine). In addition, the performance of LC-HRMS was studied in terms of linearity, sensitivity, intra- and inter-day precision, and overall robustness. The developed analytical method using LC-HRMS is a new tool for neurotoxicology research using the Daphnia magna model. As a result, general differences on the concentrations of those neurotransmitters exposed to the mentioned pharmaceuticals were observed.

Stability and toxicity studies for duloxetine and econazole on Spirodela polyrhiza using chiral capillary electrophoresis.

Stability and toxicity studies for duloxetine and econazole were achieved using individual solutions and their mixtures. Stability of drugs racemates and enantiomers was investigated under abiotic and biotic conditions. Toxicity was evaluated for the first time on Spirodela polyrhiza. EC50 values were calculated for each individual drug and for their binary mixture. Real (not nominal) concentrations determined by Capillary Electrophoresis were employed in the calculations of toxicity parameters. The use of a 25 mM phosphate buffer (pH 3.0) with 1.5% S-ß-CD as chiral selector at a temperature of 30 °C and a separation voltage of -20 kV enabled the simultaneous enantiomeric separation of duloxetine and econazole in 7.5 min with enantiomeric resolutions of 7.9 and 6.5, respectively. For individual solutions, decay percentages under abiotic conditions were higher for duloxetine (80%) than for econazole (60%), while in presence of Spirodela polyrhiza they increased for duloxetine but not for econazole. Econazole showed the highest decay percentages under abiotic or biotic conditions (100%) in binary mixtures. EC50 values for duloxetine and econazole enabled to include both drugs within the group of very toxic compounds although econazole showed a higher toxicity than duloxetine and the binary mixture.

Enantiomer stability and combined toxicity of duloxetine and econazole on Daphnia magna using real concentrations determined by capillary electrophoresis.

Enantiomer stability was investigated in this work for the first time for duloxetine and econazole in individual solutions and their mixtures under the standardized ecotoxicity test experimental conditions for Daphnia magna and abiotic conditions. Real (and not nominal) enantiomer concentrations were employed for calculations since their determination was achieved by Capillary Electrophoresis. Relevant differences were found in stability profiles for both drugs in any case. Toxicity was evaluated for the first time in this work for mixtures of duloxetine and econazole on Daphnia magna. Dose-effect parameters were calculated at different exposure times (24, 48, and 72 h) showing a significant inhibition of daphnids mobility when increasing the incubation time. Combination index values enabled to obtain the type and level of interaction of drugs with the organism. A strong synergism was observed at 48 h exposure time and any effect level, which demonstrated the high toxicity of the drug mixture compared with the individual drug solutions. These results were corroborated when evaluating the oxidative stress using fluorescence images.

Genotoxic Evaluation of Duloxetine II. The Effect on the Number of Sister Chromatid Exchanges, the Mitotic Index, and the Proliferation Kinetics in Mouse Bone Marrow.

Duloxetine is an antidepressant which has showed valuable results, particularly in patients with major depression. This type of drugs is known to require genotoxic studies as part of their preclinical safety evaluation. In the case of duloxetine, however, there have been controversial results. Therefore, we considered it worthwhile to extend studies on the matter in an attempt to reach a conclusion. The present assay was made in mouse bone marrow to evaluate the capacity of the drug to induce sister chromatid exchanges (SCE), as well as to modify the proliferation kinetics and the mitotic index. Three doses of the antidepressant were tested (2, 20, and 200 mg/kg), besides the control mice were administered with purified water, and the positive treated animals administered with 1 mg/kg of doxorubicin. The results indicated a moderate but significant increase of SCE with the three tested doses, no effect regarding the mitotic index and a small reduction in the proliferation kinetics. Although in our assay the drug showed a lower effect, the present study agreed with a previous report that analyzed the amount of micronuclei in mouse peripheral blood, and it confirmed the relevance of evaluating the genotoxic effect of antidepressants, specifically duloxetine by applying diverse tests.